It is difficult to standardize because the in vivo environment of biofilm infections varies depending on the location of the infection, hence the optimal medium should be developed for each infection, for example, medium supplemented with mucin for studying cystic fibrosis lung infection [55], or saliva containing medium for studying oral biofilms [56], or human urine for urinary tract infections [57, 58]. The gene discussed is MUC5AC; the disease is infection.